ExecuteNonQuery() won't work for INSERT function - vb.net

Question

First of all, I'm not a professional programmer. So there are some big faults possible in my program!
The problem is:
I linked my WPF file in visual express with a MS Access database (format 2003). Whenever I try to run the following (sorry for the dutch code):
Public Sub ToevoegenPersoon(voornaam As String, achternaam As String, mailadres As String, geboortedatum As Date, klantennummer As Integer, specialeCategorie As String)
Dim opdracht As OleDbCommand
Dim sqlOpdracht As String
sqlOpdracht = "INSERT INTO Klant (Voornaam, achternaam, mailadres, geboortedatum, klantennummer, specialeCategorie)" & _
"VALUES (" & Chr(34) & "" & voornaam & "" & Chr(34) & "," & Chr(34) & "" & achternaam & "" & Chr(34) & "," & Chr(34) & "" & _
mailadres & "" & Chr(34) & "," & Convert.ToString(geboortedatum) & "," & Convert.ToString(klantennummer) & "," & Chr(34) & "" & specialeCategorie & "" & Chr(34) & ")"
opdracht = New OleDbCommand(sqlOpdracht, connectie)
Debug.WriteLine(sqlOpdracht)
MsgBox(sqlOpdracht)
opdracht.Connection.Open()
opdracht.ExecuteNonQuery()
opdracht.Connection.Close()
End Sub
my program always has an error for the ExecuteNonQuery() function. This function is used for the following event:
Private Sub btnKlantToevoegen_Click(sender As Object, e As RoutedEventArgs) Handles btnKlantToevoegen.Click
Dim achternaam As String = boxVoornaam.Text
Dim voornaam As String = boxAchternaam.Text
Dim emailadres As String = boxEmailadres.Text
Dim geboortedatum As Date = GeboortedatumSelectie.SelectedDate
Dim klantennummer As Integer = 5
Dim specialeCategorie As String = "Jeugd"
Try
database.ToevoegenPersoon(voornaam, achternaam, emailadres, geboortedatum, klantennummer, specialeCategorie)
Catch ex As Exception
End Try
boxAchternaam.Clear()
boxVoornaam.Clear()
boxEmailadres.Clear()
End Sub
At the top, I stated the following to connect MS Access database with Visual express:
Private connectiestring As String = My.Settings.Database_Drijkoningen_Konings1ConnectionString
Private connectie As OleDbConnection
connectie = New OleDbConnection(connectiestring)
When running this program, the executenonquery() gives an error. And I have no clue whatsoever what it can be. Anybody who does?
Thanks in advance
Jeroen

Answer 1

Not sure if this could resolve your problem. I don't know the error message. However I will show a simple parameterized query that probably could help a lot
Public Sub ToevoegenPersoon(voornaam As String, achternaam As String, mailadres As String, geboortedatum As Date, klantennummer As Integer, specialeCategorie As String)
Dim opdracht As OleDbCommand
Dim sqlOpdracht As String
sqlOpdracht = "INSERT INTO Klant (Voornaam, achternaam, mailadres, " & _
"geboortedatum, klantennummer, specialeCategorie) " & _
"VALUES (?,?,?,?,?,?)"
opdracht = New OleDbCommand(sqlOpdracht, connectie)
opdracht.Parameters.AddWithValue("#p1", voornaam)
opdracht.Parameters.AddWithValue("#p2", achternaam)
opdracht.Parameters.AddWithValue("#p3", mailadres)
opdracht.Parameters.AddWithValue("#p4", Convert.ToString(geboortedatum))
opdracht.Parameters.AddWithValue("#p5", Convert.ToString(klantennummer))
opdracht.Parameters.AddWithValue("#p6", specialeCategorie)
opdracht.Connection.Open()
opdracht.ExecuteNonQuery()
opdracht.Connection.Close()
End Sub
Now, with a parameterized query there is no more concatenations on the command text and this alone will remove any possibility to forget some quote or comma between value. (Of course this removes also the Sql Injection problem and the parsing of strings that contain special characters)
There is still a problem to be resolved. The 4th and 5th parameter receive a string value. This requires the underlying field on the datatable to be a string field and not a DateTime. If this is not the case then you need to pass (as parameter value) just the date value